5 things you need to know about the tech of AC4

By Ian Failes

October 27, 2013

The newest installment of AC - Black Flag - is about to be released, firstly for existing platforms but also for the nex-gen PS4 and Xbox One consoles. To cater for the old and the new, Ubisoft further developed its AnvilNext engine to deliver improvements in seamless world play, ocean and environmental sims and lighting. Here's a look at five of the tech developments that will be featured in the game.

1. Seamless play

In Black Flag, players can now access the ocean from everywhere in the world at any time and interact with it. For example, they can swim from the beach and jump from the top of a ship mast into the ocean in seamless moves. To do this, Ubisoft developed a new grid system to support the huge world of the game. On top of their regular loading grid they added a new long-range grid to deal with longer distances in the ocean.

Players can now dive from ship to ocean and continue playing in the world of the game.

While on the ship, a key question for the development team was whether to give the ability for the player to let go of the wheel at any time. Originally, they only allowed the player to leave the wheel in designated areas which was a simple solution and meant programmers did not have to worry about managing 'weird scenarios', such as swimming kilometers away from the shop and entering cities while swimming. But, ultimately, Ubisoft felt this became a restriction on the player's freedom to play the game the way he/she wanted - to go anywhere. So they ended up making those 'crazy' situations work, to the benefit of the player.

Ubisoft artists at work on Black Flag.

Ubisoft also created a dynamic navmesh technology for the boarding gameplay. Part of the game might involve two ships - two totally dynamic platforms - moving somewhat independently from each other. The team wanted NPCs (non-player characters) jumping from one ship to the other. They needed to make all the navigation systems working in local referential and sometimes with two different referentials. Sometimes, a jump between two points is valid on instant but becomes impossible to jump the next second. To spice things up, Ubisoft added a custom navigation technology for NPCs to cross over using other means than regular jumping, such as rope swinging or rope shimmying.

Above: watch a 10-minute walkthrough of Black Flag's open world gameplay.

2. Upgraded ocean tech

Significant development at Ubisoft on the AnvilNext Engine had already been carried out for the oceans in Assassin's Creed III (see fxguide's previous coverage). But on Black Flag, two new properties had to be catered for. First, the game now had to support all kinds of weather, and therefore support all of the Beaufort levels to create an accurate simulation, not just the ones that they needed for the missions in AC3.

A stormy scene from Black Flag.

Secondly, the ocean tech had be made systemic, but also controllable by designers - it was important for level designers to be able to control all the settings of missions, including the ocean’s look and feel. Many visual improvements were made such as a third layer of small waves to bring out more details, better foam shading, better lighting, etc. Ubisoft also developed a new technology to recreate the look and feel of the Caribbean, with its mystical lagoons and continuity between different depths of water.

Above: watch Ubisoft's 'Building a Next Gen Open World' breakdown of Black Flag.

3. Cloth and foliage sims

Certainly, the AC games have always included a high degree of cloth simulation. Black Flag has pushed the tech even further, especially for the next-gen consoles to add more realism to the sails, tents and costumes. Dynamic foliage now makes use of simulation bones for plantlife thanks to additional CPU and GPU power, for example. But interestingly, once the team saw the results on next-gen, they had a request of 'can we have it also on current gen?' So the technical directors also added plant physics simulation (with less accuracy) on the current gen platforms as well.

A still from Black Flag.

4. Lighting on land and in sea

AnvilNext's lighting system was also rewritten to support dynamic global illumination (via deferred radiance transfer volumes) and to provide for a physically based volumetric fog, individual rendering of raindrops that are made of lit particles and that generated dynamic ripples in the wind. That translated also to the under-sea portions of the game. For Black Flag on PC, Ubisoft has also implemented the SMAA anti-aliasing tech, as well as TXAA (temporal anti-aliasing) - exclusively on Nvidia GPU. HBAO+ for improved ambient occlusion, and Tessellation, have also been implemented in Black Flag with the help of Nvidia.

Above: watch Nvidia's GeForce GTX Tech Video for Black Flag.

5. Making the game for even more platforms

Black Flag is being released for six different platforms - Microsoft Windows, PS3, PS4, Wii U, Xbox 360 and Xbox One - with the next-gen consoles a particular challenge for Ubisoft. They had to work with hardware that was still not 100 per cent finished and with SDKs that were still being developed too.

Inside Ubisoft.

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